/**
 * Copyright 2005 The Apache Software Foundation
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.mapred.lib;

import org.apache.hadoop.mapred.Partitioner;
import org.apache.hadoop.mapred.JobConf;

import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.io.Writable;

/** Partition keys by their {@link Object#hashCode()}. */
public class HashPartitioner implements Partitioner {

    @Override
    public void configure(JobConf job) {
    }

    /** Use {@link Object#hashCode()} to partition. */
    @Override
    public int getPartition(WritableComparable key, Writable value,
                            int numReduceTasks) {
        return (key.hashCode() & Integer.MAX_VALUE) % numReduceTasks;
    }

}
